when to use @ in c#?

Question

I use @ symbol with local path only, but when do I use @ exactly?

Answer 1

You use @ before strings to avoid having to escape special characters.

This from the MSDN:

Use verbatim strings for convenience and better readability when the string text contains backslash characters, for example in file paths. Because verbatim strings preserve new line characters as part of the string text, they can be used to initialize multiline strings. Use double quotation marks to embed a quotation mark inside a verbatim string. The following example shows some common uses for verbatim strings:

string filePath = @"C:\Users\scoleridge\Documents\"; //Output: C:\Users\scoleridge\Documents\

string text = @"My pensive SARA ! thy soft cheek reclined
    Thus on mine arm, most soothing sweet it is
    To sit beside our Cot,..."; /* Output: My pensive SARA ! thy soft cheek reclined    Thus on mine arm, most soothing sweet it is    To sit beside our Cot,...
*/

string quote = @"Her name was ""Sara."""; //Output: Her name was "Sara."

Answer 2

AFAIK, You can use @ at any place where you don't want to let the default meaning of the thing persist. For example, @class will make class an identifier. @bool will make bool an identifier instead of a keyword.

You know the usage of @ before strings. It is used to indicate that take all the text of the string literally and don't treat any character in the string specially.

Edit: An yes, another thing to this is that @Keyword is compiled into a Keyword in IL.

See this Link for more details.

Answer 3

Verbatim Strings

An @ before a string literal in C# denotes a verbatim string. In a verbatim string, only the quote escape sequence ("") is parsed as an escape sequence; all others, e.g. \n, \t etc. are ignored.

You'll have seen this syntax used with file paths, etc. because it's convenient to have the compiler ignore the backslashes in the path, rather than having to double-escape them, e.g.

var s = @"c:\Some\File\Path.txt";

is a little easier to read than

var s = "c:\\Some\\File\\Path.txt";

Reserved Words

You can also prefix identifiers with @ in order to allow using reserved words in identifiers. For example, @class can be used as an identifier, whereas class wouldn't be permitted. In this specific case, @class is a little less jarring (at least, I find) than the usual convention of klass or clazz which are often used to work around this restriction in other languages.

Answer 4

If you want to use keywords as variable names

string @string = "Hi";